The present invention relates to photolithography applied to, for example, the manufacture of semiconductor integrated circuits and liquid crystal panels. The present invention relates to, in particular, a mask data design method and a mask data design apparatus for conducting automatic correction processing and to a recording medium capable of reading a computer storing mask data design procedures.
In photolithography for manufacturing a semiconductor integrated circuit, as the integration of devices mounted on a wafer is higher and a design rule is narrower, the problem of so-called an optical proximity effect attracts more attention.
The "optical proximity effect" is a phenomenon that a design pattern cannot be transferred onto a wafer with a desired shape and size. The optical proximity effect is a term originally used to mean the effect of light during transfer operation. It has now been used to generally means the effect which occurs throughout wafer process.
To attain desired device performance, it is necessary to realize the desired size and form of a design pattern on a wafer even if the optical proximity effect occurs. In recent years, optical proximity effect correction or OPC which corrects a process bias on a mask in advance, has been studied vigorously since it is considered effective to correct the optical proximity effect.
To make OPC effectively to a large-scale layout, it is required to automatically execute OPC processing on a computer. Various methods have been conventionally proposed for such automatic OPC processing. They include "OPTIMASK: An OPC algorithm for chrome and phase-shift mask design" in Proc. SPIE-Int. Soc. Opt. Eng. (USA) vol. 2440: pp. 192-206 (1995); "Optical Proximity Correction, a First Look at Manufacturability" in Proc. SPIE-Int. Soc. Opt. Eng. (USA) vol. 2,322, pp. 229-238 (1994); "Simple Method of Correcting Optical Proximity Effect for 0.35 .mu.m Logic LSI Circuits" in Jpn. J. Appl. Phys. vol. 34 (1995), pp. 6,547-6,551, Part 1, No. 12B, December 1995; and "Fast Sparse Aerial Image Calculation for OPC" in Proc. SPIE-Int. Soc. Opt. Eng. (USA) vol. 2,621: pp. 534-545 (1995).
Mask data design using the conventional OPC method, however, employs a single correction method to all design patterns. This disadvantageously requires great time for correction calculation and, in some cases, accurate corrections cannot be made depending on the shape and arrangement of a mask pattern.